Estimation of the shear bond strength and adhesive remnant index of orthodontic adhesives stored in static magnetic field

Abstract

ABSTRACT Purpose Static magnetic field (SMF) affects the polymerization reaction of orthodontic adhesives. Although their effects on shear bond strength (SBS) and adhesive remnant index (ARI) are not investigated yet, the current research designed to search the impact of storage of the orthodontic composite on SMF on SBS and ARI. Materials and Methods Biofix and Heliosit orthodontic adhesives were employed in this study, beside 60 extracted premolars that were separated into two equal groups according to adhesive type. Each group, furtherly, is divided into three subgroups (10 each) according to the storage field magnetic intensity as Zero, 225 and 1000Gauss. The tensile instron machine was performed to debond the brackets after incubation for 24 h in a dark wet environment at 37C°. ARI was evaluated by stereomicroscope at 20 magnification power. SBS and ARI data were analysed by ANOVA and Kruskal–Wallis tests, respectively. P was set at 0.05. The results SBS of Heliosit adhesive significantly increased with elevation of field intensity at 8.5496, 9.7592 and 11.2129MPas, while Biofix SBS was significantly changed from 9.1547, 11.8294 and 8.7132MPas with Zero, 225 and 1000Gauss field intensity, respectively. ARI showed a non-significant difference at three storage intensities as p = 0.543, 0.377 for Biofix and Heliosit, respectively. Conclusion Storage of Biofix and Heliosit orthodontic adhesives in 225Gauss SMF improves SBS. Furthermore, an increase in SMF intensity up to 1000Gauss improves Heliosit SBS, unlike Biofix which shows significant reduction.